Louis-Jacques-Mandé Daguerre, the inventor of the daguerrotype form of photography, was born on November 18, 1787. Daguerre, a painter of theatrical backdrops for dioramas, was interested in a method that would help him improve the speed of his diorama creations. He joined a partnership with Joseph Nicéphore Niépce who had already invented the world’s first photograph, called the héliograph. Nicéphore died early in their collaboration.

By 1939, the daguerrotype was ready for the world. The surviving pictures tend to be portraits. The much rarer street scenes have virtually no people in them, not because Daguerre emptied Paris, but because the exposures were so long the people became invisible unless they were stock still. In exchange for a life-long pension for Niépce’s son and Daguerre, the French government acquired the patent and declared the process a “Free Gift to the World.” Daguerre died on July 10, 1873. His name is one of the 72 names of French men of science and invention inscribed on the base on the Eiffel Tower.

Today’s expression, il n’y a pas photo (eel knee ah pah photo), literally means “there is no photo” but figuratively is used to mean that something is absolutely certain or without doubt. The expression comes from horse racing. If the finish is close, a photo finish, the result is decided by the image. If there’s no doubt, there’s no need to resort to a photo. In a daguerrotype, however, the horses would be invisible and we’d only see the stands. Pretty cool!